Pubdate: Tue, 27 Jan 2004
Source: Guardian, The (UK)
Copyright: 2004 Guardian Newspapers Limited
Contact:  http://www.guardian.co.uk/guardian/
Details: http://www.mapinc.org/media/175
Author: David Adam

FROM THE MUNCHIES TO A SLIMMING DRUG

Sanofi's potential blockbuster obesity and anti-smoking drug
Rimonabant has its roots in efforts to understand why smoking cannabis
tends to make people feel insatiably hungry. Scientists reasoned that
if taking the drug gave people the so-called munchies, then
identifying and blocking the brain pathways responsible might stop
others overeating.

It works by binding to and blocking a receptor protein found on the
surface of brain cells. These receptors are set up to receive chemical
molecules acting as messengers, and when they do, this triggers a
chemical reaction that sends an instruction to the brain. The
scientists found that chemicals called canna-binoids, which occur
naturally in cannabis, bound to these receptors and made the cells
issue an instruction to eat.

The body also produces several cannabinoids of its own, which bind to
the same receptor and issue the same instruction. Rimonabant's trick
is that it looks similar enough to these endogenous messenger
molecules to bind the receptor, but different enough not to cause the
"eat" message to be passed on. It then tends to hang around on the
receptor protein, effectively acting as a protective cap that stops
the genuine cannabinoid signal molecules from binding.

Results from trials have shown encouraging weight loss. Obese patients
given the highest doses of the drug lost an average of 4kg each in 16
weeks compared to a control group. Scientists have found that it also
seems to suppress a nicotine addict's urge to smoke and others are
investigating whether it could be used to combat alcoholism.

Steve Alexander, a neuroscientist who works on cannabinoid receptors
at Nottingham University says drugs like Rimonabant tap into pathways
of the brain associated with pleasure. "The brain processes you
undergo as you eat nice food are very similar to what you do when you
smoke cannabis or inject heroin.
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MAP posted-by: Larry Seguin